--- /dev/null
+// Package simple contains a linter for Go source code.
+package simple
+
+import (
+ "fmt"
+ "go/ast"
+ "go/constant"
+ "go/token"
+ "go/types"
+ "path/filepath"
+ "reflect"
+ "sort"
+ "strings"
+
+ "honnef.co/go/tools/analysis/code"
+ "honnef.co/go/tools/analysis/edit"
+ "honnef.co/go/tools/analysis/lint"
+ "honnef.co/go/tools/analysis/report"
+ "honnef.co/go/tools/go/ast/astutil"
+ "honnef.co/go/tools/go/types/typeutil"
+ "honnef.co/go/tools/internal/passes/buildir"
+ "honnef.co/go/tools/internal/sharedcheck"
+ "honnef.co/go/tools/knowledge"
+ "honnef.co/go/tools/pattern"
+
+ "golang.org/x/tools/go/analysis"
+ gotypeutil "golang.org/x/tools/go/types/typeutil"
+)
+
+var (
+ checkSingleCaseSelectQ1 = pattern.MustParse(`
+ (ForStmt
+ nil nil nil
+ select@(SelectStmt
+ (CommClause
+ (Or
+ (UnaryExpr "<-" _)
+ (AssignStmt _ _ (UnaryExpr "<-" _)))
+ _)))`)
+ checkSingleCaseSelectQ2 = pattern.MustParse(`(SelectStmt (CommClause _ _))`)
+)
+
+func CheckSingleCaseSelect(pass *analysis.Pass) (interface{}, error) {
+ seen := map[ast.Node]struct{}{}
+ fn := func(node ast.Node) {
+ if m, ok := code.Match(pass, checkSingleCaseSelectQ1, node); ok {
+ seen[m.State["select"].(ast.Node)] = struct{}{}
+ report.Report(pass, node, "should use for range instead of for { select {} }", report.FilterGenerated())
+ } else if _, ok := code.Match(pass, checkSingleCaseSelectQ2, node); ok {
+ if _, ok := seen[node]; !ok {
+ report.Report(pass, node, "should use a simple channel send/receive instead of select with a single case",
+ report.ShortRange(),
+ report.FilterGenerated())
+ }
+ }
+ }
+ code.Preorder(pass, fn, (*ast.ForStmt)(nil), (*ast.SelectStmt)(nil))
+ return nil, nil
+}
+
+var (
+ checkLoopCopyQ = pattern.MustParse(`
+ (Or
+ (RangeStmt
+ key value ":=" src@(Ident _)
+ [(AssignStmt
+ (IndexExpr dst@(Ident _) key)
+ "="
+ value)])
+ (RangeStmt
+ key nil ":=" src@(Ident _)
+ [(AssignStmt
+ (IndexExpr dst@(Ident _) key)
+ "="
+ (IndexExpr src key))]))`)
+ checkLoopCopyR = pattern.MustParse(`(CallExpr (Ident "copy") [dst src])`)
+)
+
+func CheckLoopCopy(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ m, edits, ok := code.MatchAndEdit(pass, checkLoopCopyQ, checkLoopCopyR, node)
+ if !ok {
+ return
+ }
+ t1 := pass.TypesInfo.TypeOf(m.State["src"].(*ast.Ident))
+ t2 := pass.TypesInfo.TypeOf(m.State["dst"].(*ast.Ident))
+ if _, ok := t1.Underlying().(*types.Slice); !ok {
+ return
+ }
+ if !types.Identical(t1, t2) {
+ return
+ }
+
+ tv, err := types.Eval(pass.Fset, pass.Pkg, node.Pos(), "copy")
+ if err == nil && tv.IsBuiltin() {
+ report.Report(pass, node,
+ "should use copy() instead of a loop",
+ report.ShortRange(),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("replace loop with call to copy()", edits...)))
+ } else {
+ report.Report(pass, node, "should use copy() instead of a loop", report.FilterGenerated())
+ }
+ }
+ code.Preorder(pass, fn, (*ast.RangeStmt)(nil))
+ return nil, nil
+}
+
+func CheckIfBoolCmp(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ if code.IsInTest(pass, node) {
+ return
+ }
+
+ expr := node.(*ast.BinaryExpr)
+ if expr.Op != token.EQL && expr.Op != token.NEQ {
+ return
+ }
+ x := code.IsBoolConst(pass, expr.X)
+ y := code.IsBoolConst(pass, expr.Y)
+ if !x && !y {
+ return
+ }
+ var other ast.Expr
+ var val bool
+ if x {
+ val = code.BoolConst(pass, expr.X)
+ other = expr.Y
+ } else {
+ val = code.BoolConst(pass, expr.Y)
+ other = expr.X
+ }
+ basic, ok := pass.TypesInfo.TypeOf(other).Underlying().(*types.Basic)
+ if !ok || basic.Kind() != types.Bool {
+ return
+ }
+ op := ""
+ if (expr.Op == token.EQL && !val) || (expr.Op == token.NEQ && val) {
+ op = "!"
+ }
+ r := op + report.Render(pass, other)
+ l1 := len(r)
+ r = strings.TrimLeft(r, "!")
+ if (l1-len(r))%2 == 1 {
+ r = "!" + r
+ }
+ report.Report(pass, expr, fmt.Sprintf("should omit comparison to bool constant, can be simplified to %s", r),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("simplify bool comparison", edit.ReplaceWithString(pass.Fset, expr, r))))
+ }
+ code.Preorder(pass, fn, (*ast.BinaryExpr)(nil))
+ return nil, nil
+}
+
+var (
+ checkBytesBufferConversionsQ = pattern.MustParse(`(CallExpr _ [(CallExpr sel@(SelectorExpr recv _) [])])`)
+ checkBytesBufferConversionsRs = pattern.MustParse(`(CallExpr (SelectorExpr recv (Ident "String")) [])`)
+ checkBytesBufferConversionsRb = pattern.MustParse(`(CallExpr (SelectorExpr recv (Ident "Bytes")) [])`)
+)
+
+func CheckBytesBufferConversions(pass *analysis.Pass) (interface{}, error) {
+ if pass.Pkg.Path() == "bytes" || pass.Pkg.Path() == "bytes_test" {
+ // The bytes package can use itself however it wants
+ return nil, nil
+ }
+ fn := func(node ast.Node, stack []ast.Node) {
+ m, ok := code.Match(pass, checkBytesBufferConversionsQ, node)
+ if !ok {
+ return
+ }
+ call := node.(*ast.CallExpr)
+ sel := m.State["sel"].(*ast.SelectorExpr)
+
+ typ := pass.TypesInfo.TypeOf(call.Fun)
+ if typ == types.Universe.Lookup("string").Type() && code.IsCallTo(pass, call.Args[0], "(*bytes.Buffer).Bytes") {
+ if _, ok := stack[len(stack)-2].(*ast.IndexExpr); ok {
+ // Don't flag m[string(buf.Bytes())] – thanks to a
+ // compiler optimization, this is actually faster than
+ // m[buf.String()]
+ return
+ }
+
+ report.Report(pass, call, fmt.Sprintf("should use %v.String() instead of %v", report.Render(pass, sel.X), report.Render(pass, call)),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("simplify conversion", edit.ReplaceWithPattern(pass, checkBytesBufferConversionsRs, m.State, node))))
+ } else if typ, ok := typ.(*types.Slice); ok && typ.Elem() == types.Universe.Lookup("byte").Type() && code.IsCallTo(pass, call.Args[0], "(*bytes.Buffer).String") {
+ report.Report(pass, call, fmt.Sprintf("should use %v.Bytes() instead of %v", report.Render(pass, sel.X), report.Render(pass, call)),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("simplify conversion", edit.ReplaceWithPattern(pass, checkBytesBufferConversionsRb, m.State, node))))
+ }
+
+ }
+ code.PreorderStack(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
+
+func CheckStringsContains(pass *analysis.Pass) (interface{}, error) {
+ // map of value to token to bool value
+ allowed := map[int64]map[token.Token]bool{
+ -1: {token.GTR: true, token.NEQ: true, token.EQL: false},
+ 0: {token.GEQ: true, token.LSS: false},
+ }
+ fn := func(node ast.Node) {
+ expr := node.(*ast.BinaryExpr)
+ switch expr.Op {
+ case token.GEQ, token.GTR, token.NEQ, token.LSS, token.EQL:
+ default:
+ return
+ }
+
+ value, ok := code.ExprToInt(pass, expr.Y)
+ if !ok {
+ return
+ }
+
+ allowedOps, ok := allowed[value]
+ if !ok {
+ return
+ }
+ b, ok := allowedOps[expr.Op]
+ if !ok {
+ return
+ }
+
+ call, ok := expr.X.(*ast.CallExpr)
+ if !ok {
+ return
+ }
+ sel, ok := call.Fun.(*ast.SelectorExpr)
+ if !ok {
+ return
+ }
+ pkgIdent, ok := sel.X.(*ast.Ident)
+ if !ok {
+ return
+ }
+ funIdent := sel.Sel
+ if pkgIdent.Name != "strings" && pkgIdent.Name != "bytes" {
+ return
+ }
+
+ var r ast.Expr
+ switch funIdent.Name {
+ case "IndexRune":
+ r = &ast.SelectorExpr{
+ X: pkgIdent,
+ Sel: &ast.Ident{Name: "ContainsRune"},
+ }
+ case "IndexAny":
+ r = &ast.SelectorExpr{
+ X: pkgIdent,
+ Sel: &ast.Ident{Name: "ContainsAny"},
+ }
+ case "Index":
+ r = &ast.SelectorExpr{
+ X: pkgIdent,
+ Sel: &ast.Ident{Name: "Contains"},
+ }
+ default:
+ return
+ }
+
+ r = &ast.CallExpr{
+ Fun: r,
+ Args: call.Args,
+ }
+ if !b {
+ r = &ast.UnaryExpr{
+ Op: token.NOT,
+ X: r,
+ }
+ }
+
+ report.Report(pass, node, fmt.Sprintf("should use %s instead", report.Render(pass, r)),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix(fmt.Sprintf("simplify use of %s", report.Render(pass, call.Fun)), edit.ReplaceWithNode(pass.Fset, node, r))))
+ }
+ code.Preorder(pass, fn, (*ast.BinaryExpr)(nil))
+ return nil, nil
+}
+
+var (
+ checkBytesCompareQ = pattern.MustParse(`(BinaryExpr (CallExpr (Function "bytes.Compare") args) op@(Or "==" "!=") (BasicLit "INT" "0"))`)
+ checkBytesCompareRe = pattern.MustParse(`(CallExpr (SelectorExpr (Ident "bytes") (Ident "Equal")) args)`)
+ checkBytesCompareRn = pattern.MustParse(`(UnaryExpr "!" (CallExpr (SelectorExpr (Ident "bytes") (Ident "Equal")) args))`)
+)
+
+func CheckBytesCompare(pass *analysis.Pass) (interface{}, error) {
+ if pass.Pkg.Path() == "bytes" || pass.Pkg.Path() == "bytes_test" {
+ // the bytes package is free to use bytes.Compare as it sees fit
+ return nil, nil
+ }
+ fn := func(node ast.Node) {
+ m, ok := code.Match(pass, checkBytesCompareQ, node)
+ if !ok {
+ return
+ }
+
+ args := report.RenderArgs(pass, m.State["args"].([]ast.Expr))
+ prefix := ""
+ if m.State["op"].(token.Token) == token.NEQ {
+ prefix = "!"
+ }
+
+ var fix analysis.SuggestedFix
+ switch tok := m.State["op"].(token.Token); tok {
+ case token.EQL:
+ fix = edit.Fix("simplify use of bytes.Compare", edit.ReplaceWithPattern(pass, checkBytesCompareRe, m.State, node))
+ case token.NEQ:
+ fix = edit.Fix("simplify use of bytes.Compare", edit.ReplaceWithPattern(pass, checkBytesCompareRn, m.State, node))
+ default:
+ panic(fmt.Sprintf("unexpected token %v", tok))
+ }
+ report.Report(pass, node, fmt.Sprintf("should use %sbytes.Equal(%s) instead", prefix, args), report.FilterGenerated(), report.Fixes(fix))
+ }
+ code.Preorder(pass, fn, (*ast.BinaryExpr)(nil))
+ return nil, nil
+}
+
+func CheckForTrue(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ loop := node.(*ast.ForStmt)
+ if loop.Init != nil || loop.Post != nil {
+ return
+ }
+ if !code.IsBoolConst(pass, loop.Cond) || !code.BoolConst(pass, loop.Cond) {
+ return
+ }
+ report.Report(pass, loop, "should use for {} instead of for true {}",
+ report.ShortRange(),
+ report.FilterGenerated())
+ }
+ code.Preorder(pass, fn, (*ast.ForStmt)(nil))
+ return nil, nil
+}
+
+func CheckRegexpRaw(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ call := node.(*ast.CallExpr)
+ if !code.IsCallToAny(pass, call, "regexp.MustCompile", "regexp.Compile") {
+ return
+ }
+ sel, ok := call.Fun.(*ast.SelectorExpr)
+ if !ok {
+ return
+ }
+ lit, ok := call.Args[knowledge.Arg("regexp.Compile.expr")].(*ast.BasicLit)
+ if !ok {
+ // TODO(dominikh): support string concat, maybe support constants
+ return
+ }
+ if lit.Kind != token.STRING {
+ // invalid function call
+ return
+ }
+ if lit.Value[0] != '"' {
+ // already a raw string
+ return
+ }
+ val := lit.Value
+ if !strings.Contains(val, `\\`) {
+ return
+ }
+ if strings.Contains(val, "`") {
+ return
+ }
+
+ bs := false
+ for _, c := range val {
+ if !bs && c == '\\' {
+ bs = true
+ continue
+ }
+ if bs && c == '\\' {
+ bs = false
+ continue
+ }
+ if bs {
+ // backslash followed by non-backslash -> escape sequence
+ return
+ }
+ }
+
+ report.Report(pass, call, fmt.Sprintf("should use raw string (`...`) with regexp.%s to avoid having to escape twice", sel.Sel.Name), report.FilterGenerated())
+ }
+ code.Preorder(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
+
+var (
+ checkIfReturnQIf = pattern.MustParse(`(IfStmt nil cond [(ReturnStmt [ret@(Ident _)])] nil)`)
+ checkIfReturnQRet = pattern.MustParse(`(ReturnStmt [ret@(Ident _)])`)
+)
+
+func CheckIfReturn(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ block := node.(*ast.BlockStmt)
+ l := len(block.List)
+ if l < 2 {
+ return
+ }
+ n1, n2 := block.List[l-2], block.List[l-1]
+
+ if len(block.List) >= 3 {
+ if _, ok := block.List[l-3].(*ast.IfStmt); ok {
+ // Do not flag a series of if statements
+ return
+ }
+ }
+ m1, ok := code.Match(pass, checkIfReturnQIf, n1)
+ if !ok {
+ return
+ }
+ m2, ok := code.Match(pass, checkIfReturnQRet, n2)
+ if !ok {
+ return
+ }
+
+ if op, ok := m1.State["cond"].(*ast.BinaryExpr); ok {
+ switch op.Op {
+ case token.EQL, token.LSS, token.GTR, token.NEQ, token.LEQ, token.GEQ:
+ default:
+ return
+ }
+ }
+
+ ret1 := m1.State["ret"].(*ast.Ident)
+ if !code.IsBoolConst(pass, ret1) {
+ return
+ }
+ ret2 := m2.State["ret"].(*ast.Ident)
+ if !code.IsBoolConst(pass, ret2) {
+ return
+ }
+
+ if ret1.Name == ret2.Name {
+ // we want the function to return true and false, not the
+ // same value both times.
+ return
+ }
+
+ cond := m1.State["cond"].(ast.Expr)
+ origCond := cond
+ if ret1.Name == "false" {
+ cond = negate(cond)
+ }
+ report.Report(pass, n1,
+ fmt.Sprintf("should use 'return %s' instead of 'if %s { return %s }; return %s'",
+ report.Render(pass, cond),
+ report.Render(pass, origCond), report.Render(pass, ret1), report.Render(pass, ret2)),
+ report.FilterGenerated())
+ }
+ code.Preorder(pass, fn, (*ast.BlockStmt)(nil))
+ return nil, nil
+}
+
+func negate(expr ast.Expr) ast.Expr {
+ switch expr := expr.(type) {
+ case *ast.BinaryExpr:
+ out := *expr
+ switch expr.Op {
+ case token.EQL:
+ out.Op = token.NEQ
+ case token.LSS:
+ out.Op = token.GEQ
+ case token.GTR:
+ out.Op = token.LEQ
+ case token.NEQ:
+ out.Op = token.EQL
+ case token.LEQ:
+ out.Op = token.GTR
+ case token.GEQ:
+ out.Op = token.LSS
+ }
+ return &out
+ case *ast.Ident, *ast.CallExpr, *ast.IndexExpr:
+ return &ast.UnaryExpr{
+ Op: token.NOT,
+ X: expr,
+ }
+ default:
+ return &ast.UnaryExpr{
+ Op: token.NOT,
+ X: &ast.ParenExpr{
+ X: expr,
+ },
+ }
+ }
+}
+
+// CheckRedundantNilCheckWithLen checks for the following redundant nil-checks:
+//
+// if x == nil || len(x) == 0 {}
+// if x != nil && len(x) != 0 {}
+// if x != nil && len(x) == N {} (where N != 0)
+// if x != nil && len(x) > N {}
+// if x != nil && len(x) >= N {} (where N != 0)
+//
+func CheckRedundantNilCheckWithLen(pass *analysis.Pass) (interface{}, error) {
+ isConstZero := func(expr ast.Expr) (isConst bool, isZero bool) {
+ _, ok := expr.(*ast.BasicLit)
+ if ok {
+ return true, astutil.IsIntLiteral(expr, "0")
+ }
+ id, ok := expr.(*ast.Ident)
+ if !ok {
+ return false, false
+ }
+ c, ok := pass.TypesInfo.ObjectOf(id).(*types.Const)
+ if !ok {
+ return false, false
+ }
+ return true, c.Val().Kind() == constant.Int && c.Val().String() == "0"
+ }
+
+ fn := func(node ast.Node) {
+ // check that expr is "x || y" or "x && y"
+ expr := node.(*ast.BinaryExpr)
+ if expr.Op != token.LOR && expr.Op != token.LAND {
+ return
+ }
+ eqNil := expr.Op == token.LOR
+
+ // check that x is "xx == nil" or "xx != nil"
+ x, ok := expr.X.(*ast.BinaryExpr)
+ if !ok {
+ return
+ }
+ if eqNil && x.Op != token.EQL {
+ return
+ }
+ if !eqNil && x.Op != token.NEQ {
+ return
+ }
+ xx, ok := x.X.(*ast.Ident)
+ if !ok {
+ return
+ }
+ if !code.IsNil(pass, x.Y) {
+ return
+ }
+
+ // check that y is "len(xx) == 0" or "len(xx) ... "
+ y, ok := expr.Y.(*ast.BinaryExpr)
+ if !ok {
+ return
+ }
+ if eqNil && y.Op != token.EQL { // must be len(xx) *==* 0
+ return
+ }
+ yx, ok := y.X.(*ast.CallExpr)
+ if !ok {
+ return
+ }
+ yxFun, ok := yx.Fun.(*ast.Ident)
+ if !ok || yxFun.Name != "len" || len(yx.Args) != 1 {
+ return
+ }
+ yxArg, ok := yx.Args[knowledge.Arg("len.v")].(*ast.Ident)
+ if !ok {
+ return
+ }
+ if yxArg.Name != xx.Name {
+ return
+ }
+
+ if eqNil && !astutil.IsIntLiteral(y.Y, "0") { // must be len(x) == *0*
+ return
+ }
+
+ if !eqNil {
+ isConst, isZero := isConstZero(y.Y)
+ if !isConst {
+ return
+ }
+ switch y.Op {
+ case token.EQL:
+ // avoid false positive for "xx != nil && len(xx) == 0"
+ if isZero {
+ return
+ }
+ case token.GEQ:
+ // avoid false positive for "xx != nil && len(xx) >= 0"
+ if isZero {
+ return
+ }
+ case token.NEQ:
+ // avoid false positive for "xx != nil && len(xx) != <non-zero>"
+ if !isZero {
+ return
+ }
+ case token.GTR:
+ // ok
+ default:
+ return
+ }
+ }
+
+ // finally check that xx type is one of array, slice, map or chan
+ // this is to prevent false positive in case if xx is a pointer to an array
+ var nilType string
+ switch pass.TypesInfo.TypeOf(xx).(type) {
+ case *types.Slice:
+ nilType = "nil slices"
+ case *types.Map:
+ nilType = "nil maps"
+ case *types.Chan:
+ nilType = "nil channels"
+ default:
+ return
+ }
+ report.Report(pass, expr, fmt.Sprintf("should omit nil check; len() for %s is defined as zero", nilType), report.FilterGenerated())
+ }
+ code.Preorder(pass, fn, (*ast.BinaryExpr)(nil))
+ return nil, nil
+}
+
+var checkSlicingQ = pattern.MustParse(`(SliceExpr x@(Object _) low (CallExpr (Builtin "len") [x]) nil)`)
+
+func CheckSlicing(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ if _, ok := code.Match(pass, checkSlicingQ, node); ok {
+ expr := node.(*ast.SliceExpr)
+ report.Report(pass, expr.High,
+ "should omit second index in slice, s[a:len(s)] is identical to s[a:]",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("simplify slice expression", edit.Delete(expr.High))))
+ }
+ }
+ code.Preorder(pass, fn, (*ast.SliceExpr)(nil))
+ return nil, nil
+}
+
+func refersTo(pass *analysis.Pass, expr ast.Expr, ident types.Object) bool {
+ found := false
+ fn := func(node ast.Node) bool {
+ ident2, ok := node.(*ast.Ident)
+ if !ok {
+ return true
+ }
+ if ident == pass.TypesInfo.ObjectOf(ident2) {
+ found = true
+ return false
+ }
+ return true
+ }
+ ast.Inspect(expr, fn)
+ return found
+}
+
+var checkLoopAppendQ = pattern.MustParse(`
+ (RangeStmt
+ (Ident "_")
+ val@(Object _)
+ _
+ x
+ [(AssignStmt [lhs] "=" [(CallExpr (Builtin "append") [lhs val])])]) `)
+
+func CheckLoopAppend(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ m, ok := code.Match(pass, checkLoopAppendQ, node)
+ if !ok {
+ return
+ }
+
+ val := m.State["val"].(types.Object)
+ if refersTo(pass, m.State["lhs"].(ast.Expr), val) {
+ return
+ }
+
+ src := pass.TypesInfo.TypeOf(m.State["x"].(ast.Expr))
+ dst := pass.TypesInfo.TypeOf(m.State["lhs"].(ast.Expr))
+ if !types.Identical(src, dst) {
+ return
+ }
+
+ r := &ast.AssignStmt{
+ Lhs: []ast.Expr{m.State["lhs"].(ast.Expr)},
+ Tok: token.ASSIGN,
+ Rhs: []ast.Expr{
+ &ast.CallExpr{
+ Fun: &ast.Ident{Name: "append"},
+ Args: []ast.Expr{
+ m.State["lhs"].(ast.Expr),
+ m.State["x"].(ast.Expr),
+ },
+ Ellipsis: 1,
+ },
+ },
+ }
+
+ report.Report(pass, node, fmt.Sprintf("should replace loop with %s", report.Render(pass, r)),
+ report.ShortRange(),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("replace loop with call to append", edit.ReplaceWithNode(pass.Fset, node, r))))
+ }
+ code.Preorder(pass, fn, (*ast.RangeStmt)(nil))
+ return nil, nil
+}
+
+var (
+ checkTimeSinceQ = pattern.MustParse(`(CallExpr (SelectorExpr (CallExpr (Function "time.Now") []) (Function "(time.Time).Sub")) [arg])`)
+ checkTimeSinceR = pattern.MustParse(`(CallExpr (SelectorExpr (Ident "time") (Ident "Since")) [arg])`)
+)
+
+func CheckTimeSince(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ if _, edits, ok := code.MatchAndEdit(pass, checkTimeSinceQ, checkTimeSinceR, node); ok {
+ report.Report(pass, node, "should use time.Since instead of time.Now().Sub",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("replace with call to time.Since", edits...)))
+ }
+ }
+ code.Preorder(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
+
+var (
+ checkTimeUntilQ = pattern.MustParse(`(CallExpr (Function "(time.Time).Sub") [(CallExpr (Function "time.Now") [])])`)
+ checkTimeUntilR = pattern.MustParse(`(CallExpr (SelectorExpr (Ident "time") (Ident "Until")) [arg])`)
+)
+
+func CheckTimeUntil(pass *analysis.Pass) (interface{}, error) {
+ if !code.IsGoVersion(pass, 8) {
+ return nil, nil
+ }
+ fn := func(node ast.Node) {
+ if _, ok := code.Match(pass, checkTimeUntilQ, node); ok {
+ if sel, ok := node.(*ast.CallExpr).Fun.(*ast.SelectorExpr); ok {
+ r := pattern.NodeToAST(checkTimeUntilR.Root, map[string]interface{}{"arg": sel.X}).(ast.Node)
+ report.Report(pass, node, "should use time.Until instead of t.Sub(time.Now())",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("replace with call to time.Until", edit.ReplaceWithNode(pass.Fset, node, r))))
+ } else {
+ report.Report(pass, node, "should use time.Until instead of t.Sub(time.Now())", report.FilterGenerated())
+ }
+ }
+ }
+ code.Preorder(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
+
+var (
+ checkUnnecessaryBlankQ1 = pattern.MustParse(`
+ (AssignStmt
+ [_ (Ident "_")]
+ _
+ (Or
+ (IndexExpr _ _)
+ (UnaryExpr "<-" _))) `)
+ checkUnnecessaryBlankQ2 = pattern.MustParse(`
+ (AssignStmt
+ (Ident "_") _ recv@(UnaryExpr "<-" _))`)
+)
+
+func CheckUnnecessaryBlank(pass *analysis.Pass) (interface{}, error) {
+ fn1 := func(node ast.Node) {
+ if _, ok := code.Match(pass, checkUnnecessaryBlankQ1, node); ok {
+ r := *node.(*ast.AssignStmt)
+ r.Lhs = r.Lhs[0:1]
+ report.Report(pass, node, "unnecessary assignment to the blank identifier",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("remove assignment to blank identifier", edit.ReplaceWithNode(pass.Fset, node, &r))))
+ } else if m, ok := code.Match(pass, checkUnnecessaryBlankQ2, node); ok {
+ report.Report(pass, node, "unnecessary assignment to the blank identifier",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("simplify channel receive operation", edit.ReplaceWithNode(pass.Fset, node, m.State["recv"].(ast.Node)))))
+ }
+ }
+
+ fn3 := func(node ast.Node) {
+ rs := node.(*ast.RangeStmt)
+
+ // for _
+ if rs.Value == nil && astutil.IsBlank(rs.Key) {
+ report.Report(pass, rs.Key, "unnecessary assignment to the blank identifier",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("remove assignment to blank identifier", edit.Delete(edit.Range{rs.Key.Pos(), rs.TokPos + 1}))))
+ }
+
+ // for _, _
+ if astutil.IsBlank(rs.Key) && astutil.IsBlank(rs.Value) {
+ // FIXME we should mark both key and value
+ report.Report(pass, rs.Key, "unnecessary assignment to the blank identifier",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("remove assignment to blank identifier", edit.Delete(edit.Range{rs.Key.Pos(), rs.TokPos + 1}))))
+ }
+
+ // for x, _
+ if !astutil.IsBlank(rs.Key) && astutil.IsBlank(rs.Value) {
+ report.Report(pass, rs.Value, "unnecessary assignment to the blank identifier",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("remove assignment to blank identifier", edit.Delete(edit.Range{rs.Key.End(), rs.Value.End()}))))
+ }
+ }
+
+ code.Preorder(pass, fn1, (*ast.AssignStmt)(nil))
+ if code.IsGoVersion(pass, 4) {
+ code.Preorder(pass, fn3, (*ast.RangeStmt)(nil))
+ }
+ return nil, nil
+}
+
+func CheckSimplerStructConversion(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node, stack []ast.Node) {
+ if unary, ok := stack[len(stack)-2].(*ast.UnaryExpr); ok && unary.Op == token.AND {
+ // Do not suggest type conversion between pointers
+ return
+ }
+
+ lit := node.(*ast.CompositeLit)
+ typ1, _ := pass.TypesInfo.TypeOf(lit.Type).(*types.Named)
+ if typ1 == nil {
+ return
+ }
+ s1, ok := typ1.Underlying().(*types.Struct)
+ if !ok {
+ return
+ }
+
+ var typ2 *types.Named
+ var ident *ast.Ident
+ getSelType := func(expr ast.Expr) (types.Type, *ast.Ident, bool) {
+ sel, ok := expr.(*ast.SelectorExpr)
+ if !ok {
+ return nil, nil, false
+ }
+ ident, ok := sel.X.(*ast.Ident)
+ if !ok {
+ return nil, nil, false
+ }
+ typ := pass.TypesInfo.TypeOf(sel.X)
+ return typ, ident, typ != nil
+ }
+ if len(lit.Elts) == 0 {
+ return
+ }
+ if s1.NumFields() != len(lit.Elts) {
+ return
+ }
+ for i, elt := range lit.Elts {
+ var t types.Type
+ var id *ast.Ident
+ var ok bool
+ switch elt := elt.(type) {
+ case *ast.SelectorExpr:
+ t, id, ok = getSelType(elt)
+ if !ok {
+ return
+ }
+ if i >= s1.NumFields() || s1.Field(i).Name() != elt.Sel.Name {
+ return
+ }
+ case *ast.KeyValueExpr:
+ var sel *ast.SelectorExpr
+ sel, ok = elt.Value.(*ast.SelectorExpr)
+ if !ok {
+ return
+ }
+
+ if elt.Key.(*ast.Ident).Name != sel.Sel.Name {
+ return
+ }
+ t, id, ok = getSelType(elt.Value)
+ }
+ if !ok {
+ return
+ }
+ // All fields must be initialized from the same object
+ if ident != nil && ident.Obj != id.Obj {
+ return
+ }
+ typ2, _ = t.(*types.Named)
+ if typ2 == nil {
+ return
+ }
+ ident = id
+ }
+
+ if typ2 == nil {
+ return
+ }
+
+ if typ1.Obj().Pkg() != typ2.Obj().Pkg() {
+ // Do not suggest type conversions between different
+ // packages. Types in different packages might only match
+ // by coincidence. Furthermore, if the dependency ever
+ // adds more fields to its type, it could break the code
+ // that relies on the type conversion to work.
+ return
+ }
+
+ s2, ok := typ2.Underlying().(*types.Struct)
+ if !ok {
+ return
+ }
+ if typ1 == typ2 {
+ return
+ }
+ if code.IsGoVersion(pass, 8) {
+ if !types.IdenticalIgnoreTags(s1, s2) {
+ return
+ }
+ } else {
+ if !types.Identical(s1, s2) {
+ return
+ }
+ }
+
+ r := &ast.CallExpr{
+ Fun: lit.Type,
+ Args: []ast.Expr{ident},
+ }
+ report.Report(pass, node,
+ fmt.Sprintf("should convert %s (type %s) to %s instead of using struct literal", ident.Name, typ2.Obj().Name(), typ1.Obj().Name()),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("use type conversion", edit.ReplaceWithNode(pass.Fset, node, r))))
+ }
+ code.PreorderStack(pass, fn, (*ast.CompositeLit)(nil))
+ return nil, nil
+}
+
+func CheckTrim(pass *analysis.Pass) (interface{}, error) {
+ sameNonDynamic := func(node1, node2 ast.Node) bool {
+ if reflect.TypeOf(node1) != reflect.TypeOf(node2) {
+ return false
+ }
+
+ switch node1 := node1.(type) {
+ case *ast.Ident:
+ return node1.Obj == node2.(*ast.Ident).Obj
+ case *ast.SelectorExpr:
+ return report.Render(pass, node1) == report.Render(pass, node2)
+ case *ast.IndexExpr:
+ return report.Render(pass, node1) == report.Render(pass, node2)
+ }
+ return false
+ }
+
+ isLenOnIdent := func(fn ast.Expr, ident ast.Expr) bool {
+ call, ok := fn.(*ast.CallExpr)
+ if !ok {
+ return false
+ }
+ if fn, ok := call.Fun.(*ast.Ident); !ok || fn.Name != "len" {
+ return false
+ }
+ if len(call.Args) != 1 {
+ return false
+ }
+ return sameNonDynamic(call.Args[knowledge.Arg("len.v")], ident)
+ }
+
+ fn := func(node ast.Node) {
+ var pkg string
+ var fun string
+
+ ifstmt := node.(*ast.IfStmt)
+ if ifstmt.Init != nil {
+ return
+ }
+ if ifstmt.Else != nil {
+ return
+ }
+ if len(ifstmt.Body.List) != 1 {
+ return
+ }
+ condCall, ok := ifstmt.Cond.(*ast.CallExpr)
+ if !ok {
+ return
+ }
+
+ condCallName := code.CallName(pass, condCall)
+ switch condCallName {
+ case "strings.HasPrefix":
+ pkg = "strings"
+ fun = "HasPrefix"
+ case "strings.HasSuffix":
+ pkg = "strings"
+ fun = "HasSuffix"
+ case "strings.Contains":
+ pkg = "strings"
+ fun = "Contains"
+ case "bytes.HasPrefix":
+ pkg = "bytes"
+ fun = "HasPrefix"
+ case "bytes.HasSuffix":
+ pkg = "bytes"
+ fun = "HasSuffix"
+ case "bytes.Contains":
+ pkg = "bytes"
+ fun = "Contains"
+ default:
+ return
+ }
+
+ assign, ok := ifstmt.Body.List[0].(*ast.AssignStmt)
+ if !ok {
+ return
+ }
+ if assign.Tok != token.ASSIGN {
+ return
+ }
+ if len(assign.Lhs) != 1 || len(assign.Rhs) != 1 {
+ return
+ }
+ if !sameNonDynamic(condCall.Args[0], assign.Lhs[0]) {
+ return
+ }
+
+ switch rhs := assign.Rhs[0].(type) {
+ case *ast.CallExpr:
+ if len(rhs.Args) < 2 || !sameNonDynamic(condCall.Args[0], rhs.Args[0]) || !sameNonDynamic(condCall.Args[1], rhs.Args[1]) {
+ return
+ }
+
+ rhsName := code.CallName(pass, rhs)
+ if condCallName == "strings.HasPrefix" && rhsName == "strings.TrimPrefix" ||
+ condCallName == "strings.HasSuffix" && rhsName == "strings.TrimSuffix" ||
+ condCallName == "strings.Contains" && rhsName == "strings.Replace" ||
+ condCallName == "bytes.HasPrefix" && rhsName == "bytes.TrimPrefix" ||
+ condCallName == "bytes.HasSuffix" && rhsName == "bytes.TrimSuffix" ||
+ condCallName == "bytes.Contains" && rhsName == "bytes.Replace" {
+ report.Report(pass, ifstmt, fmt.Sprintf("should replace this if statement with an unconditional %s", rhsName), report.FilterGenerated())
+ }
+ return
+ case *ast.SliceExpr:
+ slice := rhs
+ if !ok {
+ return
+ }
+ if slice.Slice3 {
+ return
+ }
+ if !sameNonDynamic(slice.X, condCall.Args[0]) {
+ return
+ }
+ var index ast.Expr
+ switch fun {
+ case "HasPrefix":
+ // TODO(dh) We could detect a High that is len(s), but another
+ // rule will already flag that, anyway.
+ if slice.High != nil {
+ return
+ }
+ index = slice.Low
+ case "HasSuffix":
+ if slice.Low != nil {
+ n, ok := code.ExprToInt(pass, slice.Low)
+ if !ok || n != 0 {
+ return
+ }
+ }
+ index = slice.High
+ }
+
+ switch index := index.(type) {
+ case *ast.CallExpr:
+ if fun != "HasPrefix" {
+ return
+ }
+ if fn, ok := index.Fun.(*ast.Ident); !ok || fn.Name != "len" {
+ return
+ }
+ if len(index.Args) != 1 {
+ return
+ }
+ id3 := index.Args[knowledge.Arg("len.v")]
+ switch oid3 := condCall.Args[1].(type) {
+ case *ast.BasicLit:
+ if pkg != "strings" {
+ return
+ }
+ lit, ok := id3.(*ast.BasicLit)
+ if !ok {
+ return
+ }
+ s1, ok1 := code.ExprToString(pass, lit)
+ s2, ok2 := code.ExprToString(pass, condCall.Args[1])
+ if !ok1 || !ok2 || s1 != s2 {
+ return
+ }
+ default:
+ if !sameNonDynamic(id3, oid3) {
+ return
+ }
+ }
+ case *ast.BasicLit, *ast.Ident:
+ if fun != "HasPrefix" {
+ return
+ }
+ if pkg != "strings" {
+ return
+ }
+ string, ok1 := code.ExprToString(pass, condCall.Args[1])
+ int, ok2 := code.ExprToInt(pass, slice.Low)
+ if !ok1 || !ok2 || int != int64(len(string)) {
+ return
+ }
+ case *ast.BinaryExpr:
+ if fun != "HasSuffix" {
+ return
+ }
+ if index.Op != token.SUB {
+ return
+ }
+ if !isLenOnIdent(index.X, condCall.Args[0]) ||
+ !isLenOnIdent(index.Y, condCall.Args[1]) {
+ return
+ }
+ default:
+ return
+ }
+
+ var replacement string
+ switch fun {
+ case "HasPrefix":
+ replacement = "TrimPrefix"
+ case "HasSuffix":
+ replacement = "TrimSuffix"
+ }
+ report.Report(pass, ifstmt, fmt.Sprintf("should replace this if statement with an unconditional %s.%s", pkg, replacement),
+ report.ShortRange(),
+ report.FilterGenerated())
+ }
+ }
+ code.Preorder(pass, fn, (*ast.IfStmt)(nil))
+ return nil, nil
+}
+
+var (
+ checkLoopSlideQ = pattern.MustParse(`
+ (ForStmt
+ (AssignStmt initvar@(Ident _) _ (BasicLit "INT" "0"))
+ (BinaryExpr initvar "<" limit@(Ident _))
+ (IncDecStmt initvar "++")
+ [(AssignStmt
+ (IndexExpr slice@(Ident _) initvar)
+ "="
+ (IndexExpr slice (BinaryExpr offset@(Ident _) "+" initvar)))])`)
+ checkLoopSlideR = pattern.MustParse(`
+ (CallExpr
+ (Ident "copy")
+ [(SliceExpr slice nil limit nil)
+ (SliceExpr slice offset nil nil)])`)
+)
+
+func CheckLoopSlide(pass *analysis.Pass) (interface{}, error) {
+ // TODO(dh): detect bs[i+offset] in addition to bs[offset+i]
+ // TODO(dh): consider merging this function with LintLoopCopy
+ // TODO(dh): detect length that is an expression, not a variable name
+ // TODO(dh): support sliding to a different offset than the beginning of the slice
+
+ fn := func(node ast.Node) {
+ loop := node.(*ast.ForStmt)
+ m, edits, ok := code.MatchAndEdit(pass, checkLoopSlideQ, checkLoopSlideR, loop)
+ if !ok {
+ return
+ }
+ if _, ok := pass.TypesInfo.TypeOf(m.State["slice"].(*ast.Ident)).Underlying().(*types.Slice); !ok {
+ return
+ }
+
+ report.Report(pass, loop, "should use copy() instead of loop for sliding slice elements",
+ report.ShortRange(),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("use copy() instead of loop", edits...)))
+ }
+ code.Preorder(pass, fn, (*ast.ForStmt)(nil))
+ return nil, nil
+}
+
+var (
+ checkMakeLenCapQ1 = pattern.MustParse(`(CallExpr (Builtin "make") [typ size@(BasicLit "INT" "0")])`)
+ checkMakeLenCapQ2 = pattern.MustParse(`(CallExpr (Builtin "make") [typ size size])`)
+)
+
+func CheckMakeLenCap(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ if pass.Pkg.Path() == "runtime_test" && filepath.Base(pass.Fset.Position(node.Pos()).Filename) == "map_test.go" {
+ // special case of runtime tests testing map creation
+ return
+ }
+ if m, ok := code.Match(pass, checkMakeLenCapQ1, node); ok {
+ T := m.State["typ"].(ast.Expr)
+ size := m.State["size"].(ast.Node)
+ if _, ok := pass.TypesInfo.TypeOf(T).Underlying().(*types.Slice); ok {
+ return
+ }
+ report.Report(pass, size, fmt.Sprintf("should use make(%s) instead", report.Render(pass, T)), report.FilterGenerated())
+ } else if m, ok := code.Match(pass, checkMakeLenCapQ2, node); ok {
+ // TODO(dh): don't consider sizes identical if they're
+ // dynamic. for example: make(T, <-ch, <-ch).
+ T := m.State["typ"].(ast.Expr)
+ size := m.State["size"].(ast.Node)
+ report.Report(pass, size,
+ fmt.Sprintf("should use make(%s, %s) instead", report.Render(pass, T), report.Render(pass, size)),
+ report.FilterGenerated())
+ }
+ }
+ code.Preorder(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
+
+var (
+ checkAssertNotNilFn1Q = pattern.MustParse(`
+ (IfStmt
+ (AssignStmt [(Ident "_") ok@(Object _)] _ [(TypeAssertExpr assert@(Object _) _)])
+ (Or
+ (BinaryExpr ok "&&" (BinaryExpr assert "!=" (Builtin "nil")))
+ (BinaryExpr (BinaryExpr assert "!=" (Builtin "nil")) "&&" ok))
+ _
+ _)`)
+ checkAssertNotNilFn2Q = pattern.MustParse(`
+ (IfStmt
+ nil
+ (BinaryExpr lhs@(Object _) "!=" (Builtin "nil"))
+ [
+ ifstmt@(IfStmt
+ (AssignStmt [(Ident "_") ok@(Object _)] _ [(TypeAssertExpr lhs _)])
+ ok
+ _
+ _)
+ ]
+ nil)`)
+)
+
+func CheckAssertNotNil(pass *analysis.Pass) (interface{}, error) {
+ fn1 := func(node ast.Node) {
+ m, ok := code.Match(pass, checkAssertNotNilFn1Q, node)
+ if !ok {
+ return
+ }
+ assert := m.State["assert"].(types.Object)
+ assign := m.State["ok"].(types.Object)
+ report.Report(pass, node, fmt.Sprintf("when %s is true, %s can't be nil", assign.Name(), assert.Name()),
+ report.ShortRange(),
+ report.FilterGenerated())
+ }
+ fn2 := func(node ast.Node) {
+ m, ok := code.Match(pass, checkAssertNotNilFn2Q, node)
+ if !ok {
+ return
+ }
+ ifstmt := m.State["ifstmt"].(*ast.IfStmt)
+ lhs := m.State["lhs"].(types.Object)
+ assignIdent := m.State["ok"].(types.Object)
+ report.Report(pass, ifstmt, fmt.Sprintf("when %s is true, %s can't be nil", assignIdent.Name(), lhs.Name()),
+ report.ShortRange(),
+ report.FilterGenerated())
+ }
+ // OPT(dh): merge fn1 and fn2
+ code.Preorder(pass, fn1, (*ast.IfStmt)(nil))
+ code.Preorder(pass, fn2, (*ast.IfStmt)(nil))
+ return nil, nil
+}
+
+func CheckDeclareAssign(pass *analysis.Pass) (interface{}, error) {
+ hasMultipleAssignments := func(root ast.Node, ident *ast.Ident) bool {
+ num := 0
+ ast.Inspect(root, func(node ast.Node) bool {
+ if num >= 2 {
+ return false
+ }
+ assign, ok := node.(*ast.AssignStmt)
+ if !ok {
+ return true
+ }
+ for _, lhs := range assign.Lhs {
+ if oident, ok := lhs.(*ast.Ident); ok {
+ if oident.Obj == ident.Obj {
+ num++
+ }
+ }
+ }
+
+ return true
+ })
+ return num >= 2
+ }
+ fn := func(node ast.Node) {
+ block := node.(*ast.BlockStmt)
+ if len(block.List) < 2 {
+ return
+ }
+ for i, stmt := range block.List[:len(block.List)-1] {
+ _ = i
+ decl, ok := stmt.(*ast.DeclStmt)
+ if !ok {
+ continue
+ }
+ gdecl, ok := decl.Decl.(*ast.GenDecl)
+ if !ok || gdecl.Tok != token.VAR || len(gdecl.Specs) != 1 {
+ continue
+ }
+ vspec, ok := gdecl.Specs[0].(*ast.ValueSpec)
+ if !ok || len(vspec.Names) != 1 || len(vspec.Values) != 0 {
+ continue
+ }
+
+ assign, ok := block.List[i+1].(*ast.AssignStmt)
+ if !ok || assign.Tok != token.ASSIGN {
+ continue
+ }
+ if len(assign.Lhs) != 1 || len(assign.Rhs) != 1 {
+ continue
+ }
+ ident, ok := assign.Lhs[0].(*ast.Ident)
+ if !ok {
+ continue
+ }
+ if vspec.Names[0].Obj != ident.Obj {
+ continue
+ }
+
+ if refersTo(pass, assign.Rhs[0], pass.TypesInfo.ObjectOf(ident)) {
+ continue
+ }
+ if hasMultipleAssignments(block, ident) {
+ continue
+ }
+
+ r := &ast.GenDecl{
+ Specs: []ast.Spec{
+ &ast.ValueSpec{
+ Names: vspec.Names,
+ Values: []ast.Expr{assign.Rhs[0]},
+ Type: vspec.Type,
+ },
+ },
+ Tok: gdecl.Tok,
+ }
+ report.Report(pass, decl, "should merge variable declaration with assignment on next line",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("merge declaration with assignment", edit.ReplaceWithNode(pass.Fset, edit.Range{decl.Pos(), assign.End()}, r))))
+ }
+ }
+ code.Preorder(pass, fn, (*ast.BlockStmt)(nil))
+ return nil, nil
+}
+
+func CheckRedundantBreak(pass *analysis.Pass) (interface{}, error) {
+ fn1 := func(node ast.Node) {
+ clause := node.(*ast.CaseClause)
+ if len(clause.Body) < 2 {
+ return
+ }
+ branch, ok := clause.Body[len(clause.Body)-1].(*ast.BranchStmt)
+ if !ok || branch.Tok != token.BREAK || branch.Label != nil {
+ return
+ }
+ report.Report(pass, branch, "redundant break statement", report.FilterGenerated())
+ }
+ fn2 := func(node ast.Node) {
+ var ret *ast.FieldList
+ var body *ast.BlockStmt
+ switch x := node.(type) {
+ case *ast.FuncDecl:
+ ret = x.Type.Results
+ body = x.Body
+ case *ast.FuncLit:
+ ret = x.Type.Results
+ body = x.Body
+ default:
+ lint.ExhaustiveTypeSwitch(node)
+ }
+ // if the func has results, a return can't be redundant.
+ // similarly, if there are no statements, there can be
+ // no return.
+ if ret != nil || body == nil || len(body.List) < 1 {
+ return
+ }
+ rst, ok := body.List[len(body.List)-1].(*ast.ReturnStmt)
+ if !ok {
+ return
+ }
+ // we don't need to check rst.Results as we already
+ // checked x.Type.Results to be nil.
+ report.Report(pass, rst, "redundant return statement", report.FilterGenerated())
+ }
+ code.Preorder(pass, fn1, (*ast.CaseClause)(nil))
+ code.Preorder(pass, fn2, (*ast.FuncDecl)(nil), (*ast.FuncLit)(nil))
+ return nil, nil
+}
+
+func isStringer(T types.Type, msCache *gotypeutil.MethodSetCache) bool {
+ ms := msCache.MethodSet(T)
+ sel := ms.Lookup(nil, "String")
+ if sel == nil {
+ return false
+ }
+ fn, ok := sel.Obj().(*types.Func)
+ if !ok {
+ // should be unreachable
+ return false
+ }
+ sig := fn.Type().(*types.Signature)
+ if sig.Params().Len() != 0 {
+ return false
+ }
+ if sig.Results().Len() != 1 {
+ return false
+ }
+ if !typeutil.IsType(sig.Results().At(0).Type(), "string") {
+ return false
+ }
+ return true
+}
+
+func isFormatter(T types.Type, msCache *gotypeutil.MethodSetCache) bool {
+ // TODO(dh): this function also exists in staticcheck/lint.go – deduplicate.
+
+ ms := msCache.MethodSet(T)
+ sel := ms.Lookup(nil, "Format")
+ if sel == nil {
+ return false
+ }
+ fn, ok := sel.Obj().(*types.Func)
+ if !ok {
+ // should be unreachable
+ return false
+ }
+ sig := fn.Type().(*types.Signature)
+ if sig.Params().Len() != 2 {
+ return false
+ }
+ // TODO(dh): check the types of the arguments for more
+ // precision
+ if sig.Results().Len() != 0 {
+ return false
+ }
+ return true
+}
+
+var checkRedundantSprintfQ = pattern.MustParse(`(CallExpr (Function "fmt.Sprintf") [format arg])`)
+
+func CheckRedundantSprintf(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ m, ok := code.Match(pass, checkRedundantSprintfQ, node)
+ if !ok {
+ return
+ }
+
+ format := m.State["format"].(ast.Expr)
+ arg := m.State["arg"].(ast.Expr)
+ if s, ok := code.ExprToString(pass, format); !ok || s != "%s" {
+ return
+ }
+ typ := pass.TypesInfo.TypeOf(arg)
+ irpkg := pass.ResultOf[buildir.Analyzer].(*buildir.IR).Pkg
+
+ if types.TypeString(typ, nil) == "reflect.Value" {
+ // printing with %s produces output different from using
+ // the String method
+ return
+ }
+
+ if isFormatter(typ, &irpkg.Prog.MethodSets) {
+ // the type may choose to handle %s in arbitrary ways
+ return
+ }
+
+ if isStringer(typ, &irpkg.Prog.MethodSets) {
+ replacement := &ast.CallExpr{
+ Fun: &ast.SelectorExpr{
+ X: arg,
+ Sel: &ast.Ident{Name: "String"},
+ },
+ }
+ report.Report(pass, node, "should use String() instead of fmt.Sprintf",
+ report.Fixes(edit.Fix("replace with call to String method", edit.ReplaceWithNode(pass.Fset, node, replacement))))
+ return
+ }
+
+ if typ.Underlying() == types.Universe.Lookup("string").Type() {
+ if typ == types.Universe.Lookup("string").Type() {
+ report.Report(pass, node, "the argument is already a string, there's no need to use fmt.Sprintf",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("remove unnecessary call to fmt.Sprintf", edit.ReplaceWithNode(pass.Fset, node, arg))))
+ } else {
+ replacement := &ast.CallExpr{
+ Fun: &ast.Ident{Name: "string"},
+ Args: []ast.Expr{arg},
+ }
+ report.Report(pass, node, "the argument's underlying type is a string, should use a simple conversion instead of fmt.Sprintf",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("replace with conversion to string", edit.ReplaceWithNode(pass.Fset, node, replacement))))
+ }
+ }
+ }
+ code.Preorder(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
+
+var (
+ checkErrorsNewSprintfQ = pattern.MustParse(`(CallExpr (Function "errors.New") [(CallExpr (Function "fmt.Sprintf") args)])`)
+ checkErrorsNewSprintfR = pattern.MustParse(`(CallExpr (SelectorExpr (Ident "fmt") (Ident "Errorf")) args)`)
+)
+
+func CheckErrorsNewSprintf(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ if _, edits, ok := code.MatchAndEdit(pass, checkErrorsNewSprintfQ, checkErrorsNewSprintfR, node); ok {
+ // TODO(dh): the suggested fix may leave an unused import behind
+ report.Report(pass, node, "should use fmt.Errorf(...) instead of errors.New(fmt.Sprintf(...))",
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("use fmt.Errorf", edits...)))
+ }
+ }
+ code.Preorder(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
+
+func CheckRangeStringRunes(pass *analysis.Pass) (interface{}, error) {
+ return sharedcheck.CheckRangeStringRunes(pass)
+}
+
+var checkNilCheckAroundRangeQ = pattern.MustParse(`
+ (IfStmt
+ nil
+ (BinaryExpr x@(Object _) "!=" (Builtin "nil"))
+ [(RangeStmt _ _ _ x _)]
+ nil)`)
+
+func CheckNilCheckAroundRange(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ m, ok := code.Match(pass, checkNilCheckAroundRangeQ, node)
+ if !ok {
+ return
+ }
+ switch m.State["x"].(types.Object).Type().Underlying().(type) {
+ case *types.Slice, *types.Map:
+ report.Report(pass, node, "unnecessary nil check around range",
+ report.ShortRange(),
+ report.FilterGenerated())
+
+ }
+ }
+ code.Preorder(pass, fn, (*ast.IfStmt)(nil))
+ return nil, nil
+}
+
+func isPermissibleSort(pass *analysis.Pass, node ast.Node) bool {
+ call := node.(*ast.CallExpr)
+ typeconv, ok := call.Args[0].(*ast.CallExpr)
+ if !ok {
+ return true
+ }
+
+ sel, ok := typeconv.Fun.(*ast.SelectorExpr)
+ if !ok {
+ return true
+ }
+ name := code.SelectorName(pass, sel)
+ switch name {
+ case "sort.IntSlice", "sort.Float64Slice", "sort.StringSlice":
+ default:
+ return true
+ }
+
+ return false
+}
+
+func CheckSortHelpers(pass *analysis.Pass) (interface{}, error) {
+ type Error struct {
+ node ast.Node
+ msg string
+ }
+ var allErrors []Error
+ fn := func(node ast.Node) {
+ var body *ast.BlockStmt
+ switch node := node.(type) {
+ case *ast.FuncLit:
+ body = node.Body
+ case *ast.FuncDecl:
+ body = node.Body
+ default:
+ lint.ExhaustiveTypeSwitch(node)
+ }
+ if body == nil {
+ return
+ }
+
+ var errors []Error
+ permissible := false
+ fnSorts := func(node ast.Node) bool {
+ if permissible {
+ return false
+ }
+ if !code.IsCallTo(pass, node, "sort.Sort") {
+ return true
+ }
+ if isPermissibleSort(pass, node) {
+ permissible = true
+ return false
+ }
+ call := node.(*ast.CallExpr)
+ typeconv := call.Args[knowledge.Arg("sort.Sort.data")].(*ast.CallExpr)
+ sel := typeconv.Fun.(*ast.SelectorExpr)
+ name := code.SelectorName(pass, sel)
+
+ switch name {
+ case "sort.IntSlice":
+ errors = append(errors, Error{node, "should use sort.Ints(...) instead of sort.Sort(sort.IntSlice(...))"})
+ case "sort.Float64Slice":
+ errors = append(errors, Error{node, "should use sort.Float64s(...) instead of sort.Sort(sort.Float64Slice(...))"})
+ case "sort.StringSlice":
+ errors = append(errors, Error{node, "should use sort.Strings(...) instead of sort.Sort(sort.StringSlice(...))"})
+ }
+ return true
+ }
+ ast.Inspect(body, fnSorts)
+
+ if permissible {
+ return
+ }
+ allErrors = append(allErrors, errors...)
+ }
+ code.Preorder(pass, fn, (*ast.FuncLit)(nil), (*ast.FuncDecl)(nil))
+ sort.Slice(allErrors, func(i, j int) bool {
+ return allErrors[i].node.Pos() < allErrors[j].node.Pos()
+ })
+ var prev token.Pos
+ for _, err := range allErrors {
+ if err.node.Pos() == prev {
+ continue
+ }
+ prev = err.node.Pos()
+ report.Report(pass, err.node, err.msg, report.FilterGenerated())
+ }
+ return nil, nil
+}
+
+var checkGuardedDeleteQ = pattern.MustParse(`
+ (IfStmt
+ (AssignStmt
+ [(Ident "_") ok@(Ident _)]
+ ":="
+ (IndexExpr m key))
+ ok
+ [call@(CallExpr (Builtin "delete") [m key])]
+ nil)`)
+
+func CheckGuardedDelete(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ if m, ok := code.Match(pass, checkGuardedDeleteQ, node); ok {
+ report.Report(pass, node, "unnecessary guard around call to delete",
+ report.ShortRange(),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("remove guard", edit.ReplaceWithNode(pass.Fset, node, m.State["call"].(ast.Node)))))
+ }
+ }
+
+ code.Preorder(pass, fn, (*ast.IfStmt)(nil))
+ return nil, nil
+}
+
+var (
+ checkSimplifyTypeSwitchQ = pattern.MustParse(`
+ (TypeSwitchStmt
+ nil
+ expr@(TypeAssertExpr ident@(Ident _) _)
+ body)`)
+ checkSimplifyTypeSwitchR = pattern.MustParse(`(AssignStmt ident ":=" expr)`)
+)
+
+func CheckSimplifyTypeSwitch(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ m, ok := code.Match(pass, checkSimplifyTypeSwitchQ, node)
+ if !ok {
+ return
+ }
+ stmt := node.(*ast.TypeSwitchStmt)
+ expr := m.State["expr"].(ast.Node)
+ ident := m.State["ident"].(*ast.Ident)
+
+ x := pass.TypesInfo.ObjectOf(ident)
+ var allOffenders []*ast.TypeAssertExpr
+ canSuggestFix := true
+ for _, clause := range stmt.Body.List {
+ clause := clause.(*ast.CaseClause)
+ if len(clause.List) != 1 {
+ continue
+ }
+ hasUnrelatedAssertion := false
+ var offenders []*ast.TypeAssertExpr
+ ast.Inspect(clause, func(node ast.Node) bool {
+ assert2, ok := node.(*ast.TypeAssertExpr)
+ if !ok {
+ return true
+ }
+ ident, ok := assert2.X.(*ast.Ident)
+ if !ok {
+ hasUnrelatedAssertion = true
+ return false
+ }
+ if pass.TypesInfo.ObjectOf(ident) != x {
+ hasUnrelatedAssertion = true
+ return false
+ }
+
+ if !types.Identical(pass.TypesInfo.TypeOf(clause.List[0]), pass.TypesInfo.TypeOf(assert2.Type)) {
+ hasUnrelatedAssertion = true
+ return false
+ }
+ offenders = append(offenders, assert2)
+ return true
+ })
+ if !hasUnrelatedAssertion {
+ // don't flag cases that have other type assertions
+ // unrelated to the one in the case clause. often
+ // times, this is done for symmetry, when two
+ // different values have to be asserted to the same
+ // type.
+ allOffenders = append(allOffenders, offenders...)
+ }
+ canSuggestFix = canSuggestFix && !hasUnrelatedAssertion
+ }
+ if len(allOffenders) != 0 {
+ var opts []report.Option
+ for _, offender := range allOffenders {
+ opts = append(opts, report.Related(offender, "could eliminate this type assertion"))
+ }
+ opts = append(opts, report.FilterGenerated())
+
+ msg := fmt.Sprintf("assigning the result of this type assertion to a variable (switch %s := %s.(type)) could eliminate type assertions in switch cases",
+ report.Render(pass, ident), report.Render(pass, ident))
+ if canSuggestFix {
+ var edits []analysis.TextEdit
+ edits = append(edits, edit.ReplaceWithPattern(pass, checkSimplifyTypeSwitchR, m.State, expr))
+ for _, offender := range allOffenders {
+ edits = append(edits, edit.ReplaceWithNode(pass.Fset, offender, offender.X))
+ }
+ opts = append(opts, report.Fixes(edit.Fix("simplify type switch", edits...)))
+ report.Report(pass, expr, msg, opts...)
+ } else {
+ report.Report(pass, expr, msg, opts...)
+ }
+ }
+ }
+ code.Preorder(pass, fn, (*ast.TypeSwitchStmt)(nil))
+ return nil, nil
+}
+
+func CheckRedundantCanonicalHeaderKey(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ call := node.(*ast.CallExpr)
+ callName := code.CallName(pass, call)
+ switch callName {
+ case "(net/http.Header).Add", "(net/http.Header).Del", "(net/http.Header).Get", "(net/http.Header).Set":
+ default:
+ return
+ }
+
+ if !code.IsCallTo(pass, call.Args[0], "net/http.CanonicalHeaderKey") {
+ return
+ }
+
+ report.Report(pass, call,
+ fmt.Sprintf("calling net/http.CanonicalHeaderKey on the 'key' argument of %s is redundant", callName),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("remove call to CanonicalHeaderKey", edit.ReplaceWithNode(pass.Fset, call.Args[0], call.Args[0].(*ast.CallExpr).Args[0]))))
+ }
+ code.Preorder(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
+
+var checkUnnecessaryGuardQ = pattern.MustParse(`
+ (Or
+ (IfStmt
+ (AssignStmt [(Ident "_") ok@(Ident _)] ":=" indexexpr@(IndexExpr _ _))
+ ok
+ set@(AssignStmt indexexpr "=" (CallExpr (Builtin "append") indexexpr:values))
+ (AssignStmt indexexpr "=" (CompositeLit _ values)))
+ (IfStmt
+ (AssignStmt [(Ident "_") ok] ":=" indexexpr@(IndexExpr _ _))
+ ok
+ set@(AssignStmt indexexpr "+=" value)
+ (AssignStmt indexexpr "=" value))
+ (IfStmt
+ (AssignStmt [(Ident "_") ok] ":=" indexexpr@(IndexExpr _ _))
+ ok
+ set@(IncDecStmt indexexpr "++")
+ (AssignStmt indexexpr "=" (BasicLit "INT" "1"))))`)
+
+func CheckUnnecessaryGuard(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ if m, ok := code.Match(pass, checkUnnecessaryGuardQ, node); ok {
+ if code.MayHaveSideEffects(pass, m.State["indexexpr"].(ast.Expr), nil) {
+ return
+ }
+ report.Report(pass, node, "unnecessary guard around map access",
+ report.ShortRange(),
+ report.Fixes(edit.Fix("simplify map access", edit.ReplaceWithNode(pass.Fset, node, m.State["set"].(ast.Node)))))
+ }
+ }
+ code.Preorder(pass, fn, (*ast.IfStmt)(nil))
+ return nil, nil
+}
+
+var (
+ checkElaborateSleepQ = pattern.MustParse(`(SelectStmt (CommClause (UnaryExpr "<-" (CallExpr (Function "time.After") [arg])) body))`)
+ checkElaborateSleepR = pattern.MustParse(`(CallExpr (SelectorExpr (Ident "time") (Ident "Sleep")) [arg])`)
+)
+
+func CheckElaborateSleep(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ if m, ok := code.Match(pass, checkElaborateSleepQ, node); ok {
+ if body, ok := m.State["body"].([]ast.Stmt); ok && len(body) == 0 {
+ report.Report(pass, node, "should use time.Sleep instead of elaborate way of sleeping",
+ report.ShortRange(),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("Use time.Sleep", edit.ReplaceWithPattern(pass, checkElaborateSleepR, m.State, node))))
+ } else {
+ // TODO(dh): we could make a suggested fix if the body
+ // doesn't declare or shadow any identifiers
+ report.Report(pass, node, "should use time.Sleep instead of elaborate way of sleeping",
+ report.ShortRange(),
+ report.FilterGenerated())
+ }
+ }
+ }
+ code.Preorder(pass, fn, (*ast.SelectStmt)(nil))
+ return nil, nil
+}
+
+var checkPrintSprintQ = pattern.MustParse(`
+ (Or
+ (CallExpr
+ fn@(Or
+ (Function "fmt.Print")
+ (Function "fmt.Sprint")
+ (Function "fmt.Println")
+ (Function "fmt.Sprintln"))
+ [(CallExpr (Function "fmt.Sprintf") f:_)])
+ (CallExpr
+ fn@(Or
+ (Function "fmt.Fprint")
+ (Function "fmt.Fprintln"))
+ [_ (CallExpr (Function "fmt.Sprintf") f:_)]))`)
+
+func CheckPrintSprintf(pass *analysis.Pass) (interface{}, error) {
+ fn := func(node ast.Node) {
+ m, ok := code.Match(pass, checkPrintSprintQ, node)
+ if !ok {
+ return
+ }
+
+ name := m.State["fn"].(*types.Func).Name()
+ var msg string
+ switch name {
+ case "Print", "Fprint", "Sprint":
+ newname := name + "f"
+ msg = fmt.Sprintf("should use fmt.%s instead of fmt.%s(fmt.Sprintf(...))", newname, name)
+ case "Println", "Fprintln", "Sprintln":
+ if _, ok := m.State["f"].(*ast.BasicLit); !ok {
+ // This may be an instance of
+ // fmt.Println(fmt.Sprintf(arg, ...)) where arg is an
+ // externally provided format string and the caller
+ // cannot guarantee that the format string ends with a
+ // newline.
+ return
+ }
+ newname := name[:len(name)-2] + "f"
+ msg = fmt.Sprintf("should use fmt.%s instead of fmt.%s(fmt.Sprintf(...)) (but don't forget the newline)", newname, name)
+ }
+ report.Report(pass, node, msg,
+ report.FilterGenerated())
+ }
+ code.Preorder(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
+
+var checkSprintLiteralQ = pattern.MustParse(`
+ (CallExpr
+ fn@(Or
+ (Function "fmt.Sprint")
+ (Function "fmt.Sprintf"))
+ [lit@(BasicLit "STRING" _)])`)
+
+func CheckSprintLiteral(pass *analysis.Pass) (interface{}, error) {
+ // We only flag calls with string literals, not expressions of
+ // type string, because some people use fmt.Sprint(s) as a pattern
+ // for copying strings, which may be useful when extracing a small
+ // substring from a large string.
+ fn := func(node ast.Node) {
+ m, ok := code.Match(pass, checkSprintLiteralQ, node)
+ if !ok {
+ return
+ }
+ callee := m.State["fn"].(*types.Func)
+ lit := m.State["lit"].(*ast.BasicLit)
+ if callee.Name() == "Sprintf" {
+ if strings.ContainsRune(lit.Value, '%') {
+ // This might be a format string
+ return
+ }
+ }
+ report.Report(pass, node, fmt.Sprintf("unnecessary use of fmt.%s", callee.Name()),
+ report.FilterGenerated(),
+ report.Fixes(edit.Fix("Replace with string literal", edit.ReplaceWithNode(pass.Fset, node, lit))))
+ }
+ code.Preorder(pass, fn, (*ast.CallExpr)(nil))
+ return nil, nil
+}
projects / dotfiles / .git / blobdiff